Overdrive control system



Sept; 1.5, 1942- E. M. CLAYTOR 2,295,715

OVERDRIVE CONTROL SYSTEM Filed Dec. 9, 1940 7'0 IGNITION 7 y I INVENTOATToRNEu Patented Sept. 15, 1942 OVERDRIVE CONTROL SYSTEM Edward M.Claytor, Anderson, Ind., assignor to General Motors Corporation,Detroit, Mich., a corporation of Delaware Application December Claims.

This invention relates to the control of overdrive for automobiles andmore particularly to the type of overdrive which includes speedresponsive mechanical means in the overdrive for connecting the shaftdriven by the engine with a member which carries the planet gears whichmesh with a sun gear and also with an internal gear connected with thepropeller shaft of the automobile. This type of overdrive is disclosedin my application S. N. 241,917, filed November 23, 1938, now Patent No.2,241,631, issued May 13, 1941. This application discloses a sun gearlocking pawl which is urged by a spring normally into engagement withthe sun gear. Therefore the function of going into overdrive isresponsive to the operation of centrifugal means for connecting thepower shaft with the planet gear carrier. The function of coming out ofoverdrive is dependent upon the energization of an electromagnet orsolenoid for retracting the looking pawl against the action of itsspeed. In my Patent No. 2,241,631 I provide a system of control operatedby a switch controlled by the driver. When this switch is closed thesolenoid is energized and the engine ignition is interrupted bydisconnecting the ignition apparatus from the current source. Theinterruption of the ignition facilitates retraction of the sun gearlocking pawl by the solenoid. The ignition is restored in response tothe retraction of the pawl from engagement with the sun gear. If thesolenoid should fail to retract the pawl, the ignition will not beautomatically restored. However ignition will be restored when thedriver opens the control switch; but, obviously the solenoid will bedeenergized and the driver must make another attempt to come out ofoverdrive by reclosing the switch. The control switch is one which ispreferably operated by depression of the throttle pedal to the extentrequired for quick acceleration. The restoration of the ignition, if itis not restored by withdrawal of the pawl from the sun gear, requiresthat the driver remember to release the accelerator pedal in order thatthis switch may open.

It is an object of the present invention to provide for automaticallyrestoring the ignition in any event, regardless of failure of the pawlto be retracted from the sun gear. In other words, if the apparatusfails to come out of overdrive, the driver does not need to remember'torelease the accelerator pedal in order to restore the ignition. Toaccomplish this object I provide means which operates in response to theclosing of the control switch automatically to withhold 9, 1940, SerialNo. 369,247

ignition for a predetermined period ordinarily sufiicient for coming outof overdrive and then automatically to restore the ignition in anyevent. Further objects and advantages of the present 5- invention willbe apparent from the following description, reference being had to theaccompanying drawing wherein a preferred embodiment of the presentinvention is clearly shown.

In the drawing:

The single figure is a view partly diagrammatic, partly structuralshowing a form of overdrive mechanism equipped With the electricalcontrol apparatus which constitutes an embodiment of the invention.

Referring to the figure, numeral l indicates the driving shaft of theoverdrive mechanism. The shaft l receives its power from the changespeed gear mechanism housed in a box which would be located between theoverdrive mechanism and the engine clutch. The shaft l is provided withexternal splines 2 which mesh with internal splines 3a of the ring 3 andwith internal splines 9a of the driving member of an overrunning clutch9. The external splines 2 mesh also with internal splines 8a of acoupling member 8 to which the propeller shaft 81) may be attached. Thesplines 2 connect together the members 3 and 9 as shown in the figure,when it is desired to use the overdrive mechanism. When it is notintended that the overdrive mechanism shall be used for any considerableperiod of time, the overdrive may be entirely disconnected by moving theshaft l endwise toward the left so that its external splines 2 willengage the internal splines 8a of the member 8, thus connecting togetherthe members 8 and 9 and leaving the member 3 free. The shaft 1 issupported for axial movement at both ends. The support for the righthand end of the shaft l is not shown. At the left end of 49 the shaft Iit is provided with a reduced portion I 0. having a sliding fit withinan axially aligned recess 80 provided in the member 8.

The member 3 is connectible with the member 5 by means of a speedresponsive latch 4. Member 5 is the planet gear ring supporting one ormore planet gears 6. The planet gears 6, which are mounted upon rods 6a.extending from the ring 5, mesh with sun gear II and with an internalgear 1a supported by a frame I which oo- 50 operates with the clutchrollers 10 which in turn cooperate with the driving clutch cam 9 toreceive transmission of torque from the driving member at such times asthe driving member 9 tends to rotate ahead of the member 1. However,when the hub of the sun gear H is engaged by a sun gear pawl I2 whichdrops into a notch II a of the hub of the sun gear, then the externalgear Ia and hence its frame I are driven at a speed exceeding the speedof the clutch driving member 9. Under these conditions the member I willoverrun the clutch driving member 9.

The sun gear pawl I2 is urged downwardly into latching position by aspring I 2a confined between the head of the pawl l2 and the base It ofa pawl operating solenoid. The solenoid which lifts the sun gear pawl l2comprises a solenoid armature I 4 connected with the pawl I2 by a rodI3. The solenoid includes two magnet coils I1 and I8 which are connectedtogether at the point I I8. Coil I8 is grounded, "and coil III isconnected with the stationary contact I9 engageable by a movable contact20 and fixed to the end of a leaf spring blade 2| which is grounded. Tothe solenoid armature I4 there is fixed a rod I5 which engages the blade2| to separate the contact 20 from the contact II! when 'the solenoidarmature I4 is attracted upwardly to retract the pawl I2 from the notchHa in the sun gear hub. The terminal 118 which is common to the solenoidmagnet coils 'l! and I8 is connected by wire 22 with a source of currentthrough a relay mechanism to be'described later. The coils II'and l8 actcumulatively to'effect the attraction of the armature I4 upwardly towithdraw the latch I2 from the sun :gear. Since the amount of magneticflux required to maintain the solenoid I4 in attracted position is muchless than that required to withdraw the pawl I2 from the sun gear, themagnet coil .11 is disabled by the opening of contacts'20 and I9 whichis effected by the engagement of the rod I5'with the spring blade 2-'I.

The pawl solenoid and the engine ignition are controlled by anassembiageof relays which will now 'be' described. The relay assemblycomprisesrelays 39, 4E] and 59 mounted ona common base represented by'therecta'm'iglelill in dot-dash lines. The base 60 carries terminals "BI,62, 6'3 and 64. Terminal 6 I is connected with a battery 65 which isgrounded. Terminal '62 is connected with a control switch Icomprisingstationary contacts II and I2 and a'movabl'e contact 13 urgedaway from the stationary contact by a spring 1.4 and against a stop 15.'A switch part I6 for closing the switch is located in the path ofmovement of the accelerator pedal so that this switch maybe closed whenthe accelerator pedal is moved to substantially wide open throttleposition. Terminal 63 is connected with the engine ignition apparatusthrough a "manually operated switch 8'!) locked open by a key controlledlock. Terminal 6411s connected with the wire 22 leading to thepawlsolenoid.

'Rela'y 30 comprises a core 3I surrounded by coil 32 connected withterminals BI and -I52, and an armature 33 insulatingly supporting acontact 34 normally engaging a stationary-contact 35 and directlycarrying a contact '36 normally separated from a stationary contact 37.Contact 35 and armature '33 are connected with terminal BI.

Relay '4Elcomprises a core 4I surrounded by a magnet coil 42 connect'edbetween contact 3! of relay 30 and theterminal 30 and the terminal 64.The armature 43 of relay 4B, which is connected with terminal Iii,carries a contact 44 for normally engaging a stationary contact 45connected 'withterminal 6 3. I

R'elay5ll is a time delay relay and comprises a core I havinga pole face52 plated with a layer of nonmag netizable metal preferably chromium.

Against this chromium plated pole face 52 the armature 53 seals whenattracted toward the core 5|. Core 5I is surrounded by a magnet coil 54connected between contact 34 of relay 33 and terminal 62. Core 5I issurrounded by single turn short circuited coil 55 which retards thedecay of flux in the relay when its coil 54 is disconnected from thecurrent source. Armature 53 is connected with terminal GI and carries acontact 56 normally engaging a contact 57 connected with contact 45 ofrelay 48 and with terminal 63.

The transmission goes into overdrive automatically in response to theattainment of a certain vehicle speed. As a predetermined speedeleinents 4 of the overdrive cause the shaft I to be connected with theplanet gear carrier 5. The sun gear II is normally held stationarythrough the action'of spring I2a upon pawl I 2. When the driver wishesto take the transmission out of overdrive he depresses the acceleratorpedal to substantially wide open throttle position thereby causingswitch III to close. VI/nen switch It closes, coil 32 of relay 3% andcoil 54 of relay 53 are connected with the battery. The armature 53 ofrelay 56 is attracted downwardly so that itseals against the pole face52. Contacts 55 and 51 are then separated but ignition is still suppliedthrough contacts 44 and 45 of relay 48 which have not then opened.Armature 33 of relay 39 is attracted downwardly to connect contacts 33and 37 which causes the battery 55 to be connected with the coil 42 ofrelay 4G and with the solenoid magnet coils [l and IS. The armature 43of relay 453 is attracted downwardly to separate contacts 43 and '45thereby disconnecting the engine ignition from the battery. Although, at'the time-contacts 4'4 and 45 are separated, the contacts 34 and 35 ofrelay 30 are separated and the coil 54 of relay 51! is disconnected fromthe battery, the contact 56 is held apart from the contact 51' due tothe fact that the armature 53 had sealed on the core face 52 and thedecay of flux in the core 5| is retarded by the short circuited coil 53.Therefore the engine ignition is interrupted in order to facilitate theretraction of the pawl I2 from the sun gear I I due to the pullexerted'by the pawl solenoid.

The upward movement of the pawl I2 is accompanied by a movement of rodI5 which engages switchblade H to separate contact 24 from contact I9.This causes a main attracting coil I I to be disconnected, whilemaintaining the holding coil I'8 in operation to retain the solenoidarmature I4 in upper position. The pawl I2 is withdrawn from the sungear by action of coils II and I8; and is held retracted by coil I3alone. When contact 20 is separated from contact III the amount ofcurrent flowing through the coil 42 of relay 40 is reduced to such lowvalue that the armature 43 of relay 40 is not held down; and thecontacts 44 and 45 reengag in order to reconnect the battery with theengine ignition apparatus and thus restore the operation of the engineafter coming out of overdrive.

If, for any reason, the pawl I2 should fail to come out of overdrivewhen the solenoid is energized, the engine ignition will ultimately berestored automatically even though the driver should fail 'to releasethe accelerator pedal to permit the switch E0 to open. This restorationof the ignition in any event at a predetermined time following theclosing of switch III is effected by the time relay 59 which releasescontacts 56 and 51. at a predetermined time interval following theseparation of contacts 34 and 35 by relay 30. This time delay may be onthe order of 0.1 to 0.3 second depending on the construction of relay5|].

From the foregoing description of the construction and mode of operationof the control circuit, it is apparent that I have provided for all ofthe advantages of the control system of my application Ser. No. 241,917and have also overcome a possible disadvantage since I have provided forthe automatic restoration of engine ignition regardless of failure tocome out of overdrive.

While the embodiment of the present invention as herein disclosed,constitutes a preferred form, it is to be understood that other formsmight be adopted, all coming within the scope of the claims whichfollow.

What is claimed is as follows:

1. A control system for overdrives of the type employing mechanicalspeed responsive means for going into overdrive and having a sun-gearnormally locked by a spring urged pawl, said system comprising asolenoid for retracting the pawl when it is desired to come out ofoverdrive, a current source, a driver controlled switch for controllingenergization of the solenoid, means responsive to closure of said switchfor discontinuing engine ignition, means for restoring ignition inresponse to retraction of the sun-gear locking pawl, and means forautomatically restoring ignition a predetermined time after closure ofsaid switch independently of the status of the pawl.

2. A control system for overdrives of the type employing mechanicalspeed responsive means for going into overdrive and having a sun-gearnormally locked by a spring urged pawl, said system comprising asolenoid for retracting the pawl when it is desired to come out ofoverdrive, a current source, a driver controlled switch for controllingenergization of the solenoid, a main control relay and time lag relayhaving magnet coils which are connnected with the current source by theclosure of said switch, normally open contacts provided by the mainrelay for connecting the source and solenoid, normally closed contactsprovided by the time lag relay for connecting the source and engineignition and normally closed contacts connecting the coil of the timelag relay with the source and opened when the magnet coil of the maincontrol relay is energized.

3. A control system for overdrives of the type employing mechanicalspeed responsive means for going into overdrive and having a sun-gearnormally locked by a spring urged pawl, said system comprising asolenoid for retracting the pawl when it is desired to come out ofoverdrive, a current source, a driver controlled switch for controllingenergization of the solenoid, a main control relay and time lag relayhaving magnet coils which are connected with the current source by theclosure of said switch, normally open contacts provided by the mainrelay for connecting the source and solenoid, normally closed contactsprovided by the time lag relay for connecting the source and engineignition and normally closed contacts provided by the main relay forconnecting the coil of the time lag relay with the source and openedwhen the magnet coil of the main control relay is energized and a thirdrelay having normally closed contacts for connecting the source andengine ignition and having a magnet coil which is energized concurrentlywith the solenoid, and means responsive to the retraction of thesun-gear locking pawl for reducing current flow in the magnet coil ofthe third relay to a value such that the contacts of the third relaywill reclose and reestablish the ignition.

4. A control system for overdrives of the type employing mechanicalspeed responsive means for going into overdrive and having a sun-gearnormally locked by a spring urged pawl, said system comprising asolenoid for retracting the pawl when it is desired to come out ofoverdrive, a current source, a driver controlled switch for controllingenergization of the solenoid, a main control relay and time lag relayhaving magnet coils which are connected with the current source by theclosure of said switch, normally open contacts provided by the mainrelay for connecting the source and solenoid, normally closed contactsprovided by the time lag relay for connecting the source and engineignition and normally closed contacts provided by the main relay forconnecting the coil of the time lag relay with the source and openedwhen the magnet coil of the main control relay is energized, means forconnecting the source and ignition independently of the time lag relayand operable to open the ignition circuit when the solenoid isenergized, and means responsive to retraction of the sun gear lockingpawl for rendering said previously named means inefiective to open theignition circuit.

5. A control system for overdrives of the type employing mechanicalspeed responsive means for going into overdrive and having a sun-gearnormally locked by a spring urged pawl, said system comprising asolenoid for retracting the pawl when it is desired to come out ofoverdrive, a current source, a driver controlled switch for controllingenergization of the solenoid, a main control relay and time lag relayhaving magnet coils which are connected with the current source by theclosure of said switch, normally open contacts provided by the mainrelay for connecting the source and solenoid, normally closed contactsprovided by the time lag relay for connecting the source and engineignition and normally closed contacts connecting the coil of the timelag relay with the source and opened when the magnet coil of the maincontrol relay is energized, and a third relay having normally closedcontacts for connecting the source and engine ignition and having amagnet coil in series with the solenoid, and means responsive toretraction of the sun-gear locking pawl for reducing current flow in thesolenoid and in the magnet coil of the third relay, whereby the thirdrelay reestablishes the ignition.

6. A system according to claim 5 in which the solenoid has a mainarmature-attracting coil and an armature-holding coil in parallel, andin which the armature attracting coil is open circuited in response toretraction of the sun-gear locking pawl, thereby limiting the currentflow to that which can flow through the armature holding coil.

'7. A system of electrical control of automobile overdrives comprisingthe combination with an overdrive mechanism having a sun gear and a pawlfor restraining movement of the sun gear, of a pawl operatingelectromagnet, a current source, a switch for connecting the windings ofthe pawl magnet with the current source, a normally closed, magnetopened relay switch for connecting the current source with theautomobile engine ignition, said relay switch having a magnet coil inseries with the current source and pawl magnet windings for the purposeof opening the ignition circuit when the pawl magnet operates to retractthe pawl from the sun gear, and means responsive to the 'retractivemovement of the pawl for decreasing the amount of current flowingthrough the relay switch magnet coil whereby the relay switch reclos'esthe ignition circuit after the pawl has been retracted from the sun.gear and means operating independently of the .pawl .for restoring theignition automatically after the lapse of a predetermined time'intervalfollowing the closure of said flrst named switch.

8. Assystem of electrical control of automobile overdrives comprisingthe combination with an overdrive mechanism having a sun gear and pawlfor restraining movement of the sun gear, of a pawl operatingelectromagnet, 'a current source, a switch for connecting the winding ofthe pawl magnet with the current source, engine ignition apparatusoperated by current Ifrom the current source, means responsive tooperation of said switch for disconnecting'the current source from theignition apparatus, and means responsive to retraction of the pawl forrendering inefiective the means which disconnects the current sourcefrom the ignition apparatus and means operating independently of the:pawl for restoring 'the ignition automatically after the .lapse of aprcdetermined time interval following the '"closure of said switch.

9. A system of electrical control of automobile overdrives comprisingthe combination with an overdrive mechanism having a sun gear and a'pawlfor restraining movement of the sun gear, of a pawl "operatingelectromagnet, a current source, a switch 'for connecting the winding ofthe pawl magnet with the current source, engine ignition apparatusoperated "by current from the current source, a relay switch renderedoperative in response to operation of the first named switch fordisconnecting th'ecurrent source from the ignition apparatus, and meansresponsive to retraction of the pawl for reducing the current in themagnet coil of the relay switch in order to render said relay switchineife'ctive'to disconnect the current source from the ignitionapparatus and means operating independently of the pawl for restoringthe ignition automatically after the lapse of a predetermined timeinterval following the closure of said first named switch.

10. A system of electrical control of automobile overdrives comprisingthe combination with an overdrive mechanism having a sun gear and a:pawl for restraining movement-of the sun gear, of a pawl operatingelectromag'net having two coil windings in parallel, one being of lowresistance and the other of high resistance, at current source, aswitchfor connecting't'he windings of the pawl magnet with the currentsource, a normally closed, magnet opened relay switch for connecting thecurrent source with the automobile engine ignition, said relay switchhaving a magnet coil in series with the current source and pawl magnetwindings for the purpose tr opening the ignition circuit when the pawlmagnet operates to retract the pawl from the sun gear, and meansresponsive to the retractive movement of the pawl for causing the lowresistance winding of the pawl magnet to be opencircuited therebyincreasing the resistance "of the circuit of the relay switch magnetcoil and thereby decreasing the amount of current flowing through therelay switch magnet coil whereby the relay switch reclosesthe ignitioncircuit after the pawl has been retracted from the sun gear and meansoperating independently of the pawl for restoring the ignitionautomatically after the lapse of 'a predetermined time intervalfollowing the closure of said first named switch.

EDWARD M. CLAYTOR.

